Hey, this is so obvious I wouldn't call it advice.
Since I am more or less done expanding my machines (important ones have 9 slots, some slow ones like jam maker stay at 3...) I used diamonds I collected for Tom.
You have more or less 3 options, I'd say.
1. buy jewelry to collect vouchers
2. buy candies to gain high xp on truck orders (jelly beans give up to 1400xp on good orders)
3. what I did, use Tom to get metal bars.
(4.) get expensive stuff and sell it, but I guess when you need to do this to have money, you could improve your farming in other...fields
I didn't count, but maybe had him run 9 times. I got 8-9 bars per order, so roughly 70-80 bars. Keeps your jewlerry running for a long time and gives you vouchers in the end, too.
if anyone has some for sale I'd be happy to FP buy : )
